Drop formation via breakup of a liquid bridge in an AC electric field

Experimental results are presented for the study of drop formation mechanism in a newly proposed electrohydrodynamic (EHD) method of drop generation in an AC electric field. In the method, a small drop is generated in two stages. A pendant drop is elongated with large oscillation by an electric forc...

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Bibliographic Details
Published in:Journal of colloid and interface science 2006-10, Vol.302 (1), p.294-307
Main Authors: Lee, Beom Seok, Cho, Hye-Jung, Lee, Jeong-Gun, Huh, Nam, Choi, Jeong-Woo, Kang, In Seok
Format: Article
Language:English
Subjects:
AC electric field
Chemistry
DNA - chemistry
EHD method
Electrodes
Electromagnetic Fields
Electrowetting
Exact sciences and technology
General and physical chemistry
Insulator
Liquid bridge
Oligonucleotide Array Sequence Analysis - instrumentation
Oligonucleotide Array Sequence Analysis - methods
Oscillometry
Particle Size
Resonant frequency
Surface Properties
Water - chemistry
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Summary:Experimental results are presented for the study of drop formation mechanism in a newly proposed electrohydrodynamic (EHD) method of drop generation in an AC electric field. In the method, a small drop is generated in two stages. A pendant drop is elongated with large oscillation by an electric force in the first stage. Then, it undergoes formation and breakup of a liquid bridge between the upper nozzle and the insulator-coated lower flat plate in the second stage. It is found that there exists a resonant frequency for maximum oscillation, which leads to an efficient drop formation in the latter stage. It is also found that breakup of liquid bridge is accelerated by the electrowetting tension acting on the drop perimeter contacting the insulator-coated flat plate. Thus the whole procedure of drop formation depends heavily on the frequency of AC field and the properties of the insulator such as hydrophilicity, thickness, and the dielectric constant. It is demonstrated that a wide range of drop size, from picoliter to nanoliter, can be obtained by controlling such key parameters without changing the nozzle diameter. Mechanism in a newly proposed EHD method of drop formation in an AC electric field is studied and it is divided into two stages, such as drop elongation and breakup of a liquid bridge.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2006.05.060